Richardson Thomas O, Liechti Jonas I, Stroeymeyt Nathalie, Bonhoeffer Sebastian, Keller Laurent
Department of Ecology and Evolution, University of Lausanne, Switzerland.
Department of Environmental Systems Science, ETH Zürich, Switzerland.
PLoS Comput Biol. 2017 May 10;13(5):e1005527. doi: 10.1371/journal.pcbi.1005527. eCollection 2017 May.
Rhythmical activity patterns are ubiquitous in nature. We study an oscillatory biological system: collective activity cycles in ant colonies. Ant colonies have become model systems for research on biological networks because the interactions between the component parts are visible to the naked eye, and because the time-ordered contact network formed by these interactions serves as the substrate for the distribution of information and other resources throughout the colony. To understand how the collective activity cycles influence the contact network transport properties, we used an automated tracking system to record the movement of all the individuals within nine different ant colonies. From these trajectories we extracted over two million ant-to-ant interactions. Time-series analysis of the temporal fluctuations of the overall colony interaction and movement rates revealed that both the period and amplitude of the activity cycles exhibit a diurnal cycle, in which daytime cycles are faster and of greater amplitude than night cycles. Using epidemiology-derived models of transmission over networks, we compared the transmission properties of the observed periodic contact networks with those of synthetic aperiodic networks. These simulations revealed that contrary to some predictions, regularly-oscillating contact networks should impede information transmission. Further, we provide a mechanistic explanation for this effect, and present evidence in support of it.
节律性活动模式在自然界中无处不在。我们研究一个振荡生物系统：蚁群中的集体活动周期。蚁群已成为生物网络研究的模型系统，这是因为其组成部分之间的相互作用肉眼可见，还因为由这些相互作用形成的按时间顺序排列的接触网络充当了信息和其他资源在整个蚁群中分布的基础。为了理解集体活动周期如何影响接触网络的传输特性，我们使用了一个自动跟踪系统来记录九个不同蚁群中所有个体的运动。从这些轨迹中，我们提取了超过两百万次蚁与蚁之间的相互作用。对整个蚁群相互作用和运动速率的时间波动进行时间序列分析表明，活动周期的周期和振幅都呈现出昼夜周期，其中白天的周期比夜间的周期更快且振幅更大。使用源自流行病学的网络传播模型，我们将观察到的周期性接触网络的传播特性与合成非周期性网络的传播特性进行了比较。这些模拟结果表明，与一些预测相反，有规律振荡的接触网络应该会阻碍信息传播。此外，我们为这种效应提供了一个机制性解释，并给出了支持它的证据。
